I do care what other people believe about reality because I don't live in a vacuum. Bad ideas and attitudes can and often do lead to bad behavior, that undermines my interests and survival, because I have to coexist and share this world with them. It behooves me to challenge such beliefs and to get my own cherished assertions scrutinized as well. You may not care if you're living in a community full of people with irrational, dogmatic, sectarianistic, ethnocentric, xenophobic, sexist, racist, and imperialistic. etc. ideals, but I do.